Shawn Crawford denied fellow-American Justin Gatlin a sprint double as he set up a United States clean sweep in the Olympic men's 200 metres on Thursday.

The race, though, was marred by ugly scenes and delayed for five minutes when the packed 75,000 crowd at the Olympic Stadium began booing and chanting "Kenteris, Kenteris!" and "Hellas, Hellas!"

Costas Kenteris, Greece's 2000 Olympic champion in the event, withdrew from the Games after missing a drugs test in mysterious circumstances the day before the opening ceremony. There was no Greek runner in Thursday's race.